Addressing COVID-19 pandemic was challenging in a resource constrained developing country. Limited health care facilities and large vulnerable population, many of whom were already burdened with comorbid conditions posed challenges on every dimension. This retrospective study highlights the clinical profile of children with SARS-CoV-2 infection from a tertiary care pediatric teaching hospital in northern India. Most of the children were either asymptomatic contacts or had mild flu-like symptoms. The most common presentation was fever followed by cough and fast breathing, but a substantial proportion had gastrointestinal symptoms as well. A significant proportion of children required admission due to associated comorbidities and severe illness. The authors also observed a higher rate of complications and mortality in the present study, presumably attributed to referral bias to the authors' center (higher proportion of critically ill children) and the presence of comorbidities. The adverse outcomes were more commonly seen in infants and children more than 10 y of age.
The trend of total footfall of children attending the hospital was proportional to the lockdown and the unlock phase of the country (April to October 2020). However, the secondary peak in number of cases in September–October was associated with the return of the migrant population, overcrowding and the seasonal influence of surge in vector borne diseases (dengue, malaria) observed in the city. The mean age and sex distribution of children admitted with SARS-CoV-2 infection in this study was comparable with the studies published elsewhere . Children of all age groups were susceptible to COVID-19 infection as reported elsewhere [14, 15]. Although the clinical features of COVID-19 illness in children are diverse, still fever and cough were the most common symptoms reported in this cohort. The spectrum of clinical features reported in other published studies are heterogeneous depending on the setting and the cohort analyzed [5, 16]. Unlike the studies on disease severity from different settings, more than two third of the admitted cases in this study had severe to critical illness. Similar to the results reported by Dong et al. , infants were more vulnerable to SARS-CoV-2 infection and had more severe disease. However, the data on relationship of disease severity and gender are limited in children.
A striking observation of this study was that a high proportion of children with SARS-CoV-2 infection required admission in view of their underlying comorbid illness. Comorbidities among children with SARS-CoV-2 have been reported in studies from China , India (61%)  and US/Canada (83%) . Around 50% of children admitted with COVID-19 illness in this cohort had undernutrition and thinness that further compounded the severity of illness and morbidity. No comprehensive data are yet available on the impact of SARS-CoV-2 on children who are well and in those with an underlying illness; but it is reasonable to consider that the latter might be at an increased risk of severe disease. The mortality rate observed in this study is much higher than that reported globally in both children and adults [19, 20]. The proposed reasons for this observation are referral bias and admissions of the most critically ill children, higher transportation time due to limited means during lockdown, comorbidities, malnutrition and infections prevalent in the authors' setting.
Contrary to published literature on laboratory parameters [18,19,20,21,22,23], a higher proportion of children in this study had anemia, leucocytosis, thrombocytopenia and elevated D-dimers. It can be attributed to higher rate comorbid illness (leukemia), secondary bacterial infections and sepsis in the authors' patients. However, the proportion of children with hypoalbuminemia, high serum ferritin levels and elevated CPK-MB levels were similar to that reported in previous studies [21,22,23]. Most of the admitted children had severe and critical illness that resulted in higher proportion of them with these biomarkers of inflammation.
In contrast to the available literature on ventilation in SARS-CoV-2 , a higher proportion of children in the present study required oxygen and ventilatory support. The presence of comorbidities, like pulmonary tuberculosis, tubercular meningitis, disseminated staphylococcus infections and liver abscess accounted for increased need of respiratory support in the children included in the study. Children with MIS-C seen in this study was similar to previous reports from India  and other parts of the world [26, 27].
The study has its share of limitations of retrospective design and lack of long term follow up of comorbidities after discharge. In spite of these shortcomings, this study provides preliminary data on clinical characteristics and outcomes of COVID-19 in children from Northern India.